The present invention relates to a tool size measuring apparatus for NC machine tools, which automatically measures the dimensions, i.e., outer diameter and length of each of a large number of tools accommodated in a tool magazine of an NC machine tool and inputs or writes the actual measurements into the machining program.
Generally, methods which have heretofore been used for measuring the dimensions, i.e., outer diameter and length of the tools in NC machine tools include one in which prior to the accommodation of the tools in the tool magazine each of the tools is measured by a separate tool presetter and the measurements are inputted into the program and another in which after a tool has been fitted into the spindle the length of the tool is measured and its value is compensated thereby inputting the same into the program. However, the conventional measuring apparatus of these types have the disadvantages of requiring the stoppage of the operation of the machine tool for tool size measuring purposes and so on.